1. Field of the Invention
The present invention is related to methods of video surveillance and, in particular, to a method for verification integrity and validity of live or recorded surveillance video.
2. Description of the Related Art
Video surveillance is currently one of the fastest growing applications of digital video and data networking. Conventional video surveillance systems employ CCTV (Closed Circuit Television) equipment that does not have the efficiency and security of digital technologies. However, transitioning the entire system into the digital domain often comes at an enormous cost.
Typically, digital video surveillance systems employ mainstream TCP/IP and Ethernet data communications standards, allowing to find adequate digital equivalents to the past and present analog architectures and to take advantage of the added levels of versatility that digital technology offers. The digital surveillance systems improve upon the efficiency of conventional systems and provide additional improvement in the level of security. However, digital surveillance systems impose a number of challenges that need to be addressed.
Implementation of an all-digital video security system involves finding ways to improve the system security while maintaining its affordability. However, once a digital video system becomes a key component of a physical security of a site, it can no longer be assumed that the surveillance video feeds are unaltered or not tempered with. A physical security system must be protected from tamper or sabotage without imposing additional expenses in its implementation.
Conventional video surveillance (i.e., CCTV) has been an important security tool in both private corporate and public government sectors. Video surveillance technology is currently evolving from entirely analogue systems on to hybrid analogue-digital systems and ultimately to all-digital IP-network based configurations. Conventional analogue CCTV systems consist of analogue cameras, display monitors and video cassette recorders.
In modern hybrid systems, the VCRs are replaced with a digital recording system utilizing digital components that digitize and compress the video signal and store it onto computer hard disks or other digital media. Some hybrid video surveillance systems have their display monitors fed from the digital recorders rather than from the analog source. Such a security system displays digitized video stream on the observation monitors. In this case, the digital recording system replaces the analog video routing switches, as well as the VCR.
Ultimately, the market exhibits an obvious trend towards an all-digital Internet Protocol (IP)-based network, where video digitization and compression are performed within a digital camera. The imminent transition to an all-digital IP-based digital video surveillance system has a potential for reducing equipment and maintenance costs while increasing the value of the system and providing improved security.
However, transition to an all-digital system creates new types of vulnerabilities and weaknesses that need to be identified and mitigated. For example, the following issued can affect a digital video surveillance. A deliberate attack on a security video system can include a deliberate insertion of false imagery and disabling of certain system components. The insertion of the false imagery can be performed at one of many points in the system:
(a) a still picture can be placed in front of the camera lens that resembles the observed scene, to simulate inactivity;
(b) previously recorded images that form a given scene are fed in a “loop” into the system, instead of the actual live video signal;
(c) display monitors located in the security monitoring center can be re-routed to display a pre-recorded video instead of a live video feed;
(d) a security video monitor can be reconfigured for viewing unrelated video content; and
(e) a digital recording file can be replaced by a file generated before or after an intrusion event, and a time stamp of the file can be falsified so that the file seem to represent the time period of the intrusion.
Additionally, any technical malfunctions can result in some of the above scenarios. Regardless of the nature of these occurrences, they need to be detected using the same methodology. Another existing problem with surveillance or other video (i.e., such as, for example, advertising video feeds) is implementation of “proof-of-play” features. An owner of a video content needs a proof that his content has been displayed a certain number of times on several screens. Therefore, a reliable method for automatically generating the proof-of-play data for a video stream is required.
A conventional way of providing the proof-of-play is generating an audit log reflecting screen ID, video clip ID and a time of display. The main disadvantage of this method is that there is no assurance that the display connected to the media player is operational or is configured to display video stream provided by the video player.
This problem can be overcome by connection of a slow-speed auxiliary digital cable (e.g., using a serial standard RS-232) for validation that the display screen is turned on and is configured to receive the video feed from a particular video player. This method is rather complex and is not reliable, as it depends on display implementation and type and a lack of standardization in TV display manufacturing.
Another problem related to producing a reliable audit log is that the media player itself can malfunction (i.e., a video decoder can malfunction, a video scheduling module can malfunction, a compressed video file can be corrupted, etc.) and generate a false audit log indicating, for example, that the video content was displayed while no video feed was rendered to a user. Such malfunctions of the video player cannot be detected without human intervention with existing technology.
Yet another conventional method for providing the proof-of-play involves insertion of a subtle audio signal into the content's audio track. This method, however, requires sophisticated digital signal processing that must be implemented at each display screen. This produces a very costly overhead to the video system. Furthermore, the reliability of this approach is also limited. In cases when malfunction only affects the video and not the audio track, it will not be detected.
Accordingly, there is a need in the art for a cost-effective method for verification of a digital video. Such method should include inserting certain distinguishable and difficult to imitate characteristics into frames of a video signal at the earliest possible point (i.e., close to a video generation source) and performing inspection of the video stream at any subsequent point in reproduction of the video footage without system modification and deployment of additional cabling.